1. Technical Field
The present invention relates to a printed circuit board having electronic components embedded therein.
2. Description of the Related Art
Generally, a printed circuit board is manufactured by forming circuit patterns with copper clad laminate on one side or both sides of a board made of various thermosetting resins, arranging and fixing ICs or electronic components on the board, forming circuit patterns therebetween and coating it with insulating material.
In order to realize a printed circuit board including electronic components embedded therein, there exists a wide variety of surface-mounting technologies for mounting semiconductor devices such as Integrated Circuit (IC) chips on a printed circuit board. The surface-mounting technologies may include a wire bonding technology and a flip chip technology.
Among these, a surface-mounting process using the wire bonding technology is configured in a manner such that an electronic component, on which a designed circuit is printed, is bonded on a printed circuit board using adhesive, metal terminals (i.e., pads) of the electronic component are connected to lead frames of the printed circuit board via metal wires for the transmission and reception of information therebetween, and the electronic component and the wires are subjected to a molding process using thermosetting resin or thermoplastic resin.
Meanwhile, a surface-mounting process using the flip chip technology is configured in a manner such that external connecting terminals (i.e., bumps) having a size ranging from several tens to several hundreds of μm are formed on an electronic component using materials such as gold, solder and other metals, the electronic component including the bump formed thereon is flipped over so that the surface of the component faces a printed circuit board, and the electronic component is mounted on the printed circuit board on the other side, that is, flipped over, unlike the process using existing wire bonding technology.
Since these surface-mounting processes are conducted in a common manner in which an electronic component is mounted on the surface of a printed circuit board, the total thickness of the resulting product after the mounting process cannot be less than the sum of the thicknesses of the printed circuit board and the electronic component, thus making the manufacture of a high-density product difficult. In addition, since electrical connection between the electronic component and the printed circuit board is achieved using the connecting terminals (pads or bumps), the electrical connection may be damaged or may malfunction due to breakage or corrosion of the connecting terminals, thus deteriorating the reliability of the product.
For this reason, in order to overcome the above problems, electronic components are embedded inside rather than outside the printed circuit board, and a build-up layer is formed for the electrical connection, thereby achieving compact and high-density products, and avoiding deterioration in the reliability occurring at a stage of connecting components to each other in the surface-mounting process using the wire bonding technology or the flip chip technology.
In the printed circuit board having electronic components embedded therein, each of electronic components must be provided with power, which is generally supplied through the circuit patterns of the printed circuit board. In this case, a number of electronic components are mounted on the board, so that the number of the circuit patterns for supplying power is increased, thereby increasing the complexity of the circuit patterns and generating power loss.
Furthermore, in the case where the electronic components are mounted in the printed circuit board, problems related with heat generation occur, and it is hard to remove interferences in RF elements.
An existing printed circuit board having electronic components embedded therein has a multi-layer structure where ground patterns for performing grounding acts and power supply patterns for applying predetermined power to the board are separately formed among circuit patterns.
Such a printed circuit board has limits in the magnitude and design of the circuit patterns when the ground patterns and the power supply patterns are formed thereon. Therefore, the locations of the electronic components to which power must be supplied are also limited.
Furthermore, there is a problem in that, when abnormal current/voltage occurs in the printed circuit board, it is applied to the electronic components, causing damage in the electronic components.